Tanning



UNITED srarss FAT-ENE @FFHQE.

ADOLF lib MEIR, OF STU'ITGART, GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE CHEMICAL FOUNDATION, INC., A CORPORATION OF DELAWARE.

Patented Nov. 1, 1921.

r TANNING.

1,395,733, Specification of Letters Patent.

Ho Drawing. Application filed December 23, 1916.

To all whom it may concern:

Be it known that I, Anonr R-6MER, citizen of the German Empire, residing at Stuttgart, Germany have invented new and useful Improvements in Tanning, of which the following is a specification.

The present invention relates to the method of tanning skins and more particularly to tanning by means of synthetic condensation products of formaldehyde and aromatic compounds. It is known that certain aromatic compounds give insoluble prod:

ucts when they are brought together, in aqueous solution, with formaldehyde and according to the present invention 1 make use of this reaction for tanning skins by treating the skins alternately with formaldehyde and with an aqueous solution of a compound which has the property of giving insoluble condensation products with formaldehyde. When the said compound is suificiently soluble in water to be dissolved in the tanning bath, such as for instance resorcinol, it can be used in the free state, otherwise it can be used in the form of a salt or other derivative; for instance I can use alkali salts of the naphthols, salts of the naphthylamins with acids and so on. By this process, the insoluble formaldehyde condensation product is formed in the fiber of the skin and is thereby intimately attached thereto. Generally I have found it preferable first to act on the skin with formaldehyde and then with the solution-of the aromatic compound, but often the reverse succession can be employed, if the aromatic compound is sulficiently retained by the fiber. If desired the succession of said steps can be repeated several times.

Serial No. 138,665.

In order to illustrate my invention. more fully I give the following example, but the invention is of course not confined to this example:

The hide to be tanned is first treated with a bath containing 2 to 5 per cent. of -lormaldehyde, during one or several days according to the thickness of the skin. Then the hide is treated with a bath containing say 1 to 2 per cent. of alpha-naphthylamin chlorhydrate during several days, where upon the leather is finished in the usual way. The properties of the leather may be modified by varying the time of treatment, the concentrations employed or by adding other substances, for instance tanning substances oi vegetable nature.

Now what I claim is:

1. The process of tanning which comprises treating the skins in a bath containing formaldehyde and subsequently in a bath containing a salt of a naphthylamin.

2. The process of tanning which comprises treating the skins in a bath containing tormaldehyde and subsequently in a bath containing an alphanaphthylaminchlorhydrate.

3. The process of tanning which comprises treating the skins in a bath containing formaldehyde and subsequently in a bath containing a soluble aromatic compound containing an animo group and capable of forming an insoluble product with formaldehyde.

In testimony whereof I have hereunto set my hand.

DR. ADULF RUMEB.

In presence of EnNnsT ENTEMANN, FRIEDA KLAIBER. 

